1. Field of the Invention
The present invention relates to devices for recording information on and reading information from a moving magnetic tape, and in particular relates to a method for shortening the stop distance of the tape with the added advantage of reducing the system load in the tape device.
2. Description of the Prior Art
In digital magnetic devices having high recording density, as well as in magnetic tape devices operating according to the GCR method, the nominal inter-block space is approximately 7.62 mm. The inter-block space is defined by the sum of a stop distance and a start distance, i.e., the sum of the distances which the tape travels due to the inertia of the system after a stop order is received, and the distance the tape moves before it comes up to speed after a start order is received.
High tape velocities are required in order to rapidly read and write information stored on magnetic tape, and the corresponding high acceleration values associated with such high velocities result in tape vibrations upon starting the device, i.e., starting the motor which moves the tape. Such vibrations can be lessened by selecting low values for the starting tape acceleration, however, this approach results in a lengthening of the starting distance and in a lengthening of the inter-block space, so that less information can be stored on a given length of magnetic tape.
One approach to the problem of shortening the entire stop distance while retaining the nominal value of the inter-block space has been to design the read signal evaluation electronics in such a manner that a read-out of the recorded information can take place with a tape velocity decrease of only 30% of the nominal velocity. This method, however, has the disadvantage that deviations in the tape velocity caused by tape vibrations can give rise to erroneous readings and subsequent evaluations errors because the read-out is still occurring in an area of strong tape retardation.